"We just get behind the people who want to get on in life - the doers, the risk-takers.

"They call us the party of the better-off. No, we're the party of the want-to-be-better-off."

The new focus on 'strivers' comes from research showing many people who hold views similar to the Tories are put off by the party's 'toff' image, typified by Andrew Mitchell's rant against 'plebs' outside Downing Street.

Ahead of the speech, Cameron said he was going to "level" with the British people about the country's economic difficulties. The prime minister proceeded to paint a gloomy portrait of the challenges facing the UK.

Cameron argued countries on the rise – such as India or China – are "lean, fit, obsessed with enterprise" while countries on the slide are "fat, sclerotic, over-regulated, spending money on unaffordable welfare systems".

He added: "I sit in those European Council meetings where we talk endlessly about Greece while, on the other side of the world, China is moving so fast it's creating a new economy the size of Greece every three months.

"I am not going to stand here as prime minister and allow this country to join the slide."

There was no mention of the environment, which will upset green campaigners. Likewise, there were few mentions of law and order issues, which will irritate rank-and-file Tories.

But the reception in the hall was broadly positive, with Cameron eloquently expressing a Conservative agenda across a range of areas.

The reception among political commentators online was also strong, if not as enthusiastic as during Miliband's 'one nation' speech last week.

The prime minister appeared to nearly break down when he discussed his son, Ivan, who died in 2009.

"I am so grateful for what all those paralympians did," he said.

"When I used to push my son Ivan around in his wheelchair, I always thought that some people saw the wheelchair, not the boy.

"Today more people would see the boy and not the wheelchair – and that’s because of what happened here this summer."

In another touching section, Cameron spoke about his father, who also had disabilities, and what he had taught him. He described his upbringing as "not a hard luck story, but a hard work story".

He added: "Work hard, family comes first, but put back in to the community too.

"There is nothing complicated about me.

"I believe in working hard, caring for my family and serving my country."

Shadow Cabinet Office minister Michael Dugher commented: "This was a defensive speech, from an out of touch, clearly rattled leader, who cannot be the 'one nation' prime minister we need.

"David Cameron never once mentioned the double dip recession or the one million young people out of work."

The speech brings the 2012 conference season to a close. MPs return to Westminster next week for the start of the new parliamentary term.